@Article{Blackburn_de Rijke:1997,
AUTHOR = {Blackburn, Patrick and de Rijke, Maarten},
TITLE = {Why Combine Logics?},
YEAR = {1997},
JOURNAL = {Studia Logica. An International Journal for Symbolic Logic},
VOLUME = {59},
NUMBER = {1},
PAGES = {5-27},
NOTE = {but published later} }
